Simultaneous accumulation of low-molecular-mass RNA at the interface along with accumulation of high-molecular-mass RNA on aqueous two-phase system partitioning

On partitioning in the potassium phosphate–PEG aqueous two-phase system, the simultaneous accumulation of the low-molecular-mass RNA at the interface along with accumulation of the coexisting high-molecular-mass RNA was quantitatively shown. The low-molecular-mass RNA was inherently partitioned between the top and bottom phases if partitioned alone. However, the low-molecular-mass RNA was caught in the interface to a significant extent if partitioned with the coexisting high-molecular-mass RNA. The degree of the accumulation of low-molecular-mass RNA increased with an increase in the content of the coexisting high-molecular-mass RNA, while the high-molecular-mass RNA was mostly accumulated at the interface.